Mobile communication device

ABSTRACT

An object of the invention is, in a mobile communication apparatus allowing to perform a transmission/reception simultaneous operation, and in a case that transmission/reception is performed by packet communication or the like, to improve reception sensitivity at a timing when only a reception processing is performed and to improve transmission distortion characteristics at a timing when only a transmission processing is performed. In the mobile communication apparatus of the invention, an antenna switching unit ( 16 ) is connected to an antenna ( 11 ). The antenna switching unit ( 16 ) includes switches ( 21 ), ( 22 ), ( 23 ) and ( 24 ), and in a case that a transmission/reception simultaneous operation is performed by packet communication or the like, a transmission side filter ( 12 ) and a reception side filter ( 14 ) constituting an antenna switching unit are connected to the antenna ( 11 ). At a timing when there is no transmission signal, a transmission system is disconnected from the antenna ( 11 ) by the switches ( 21 ) and ( 23 ), and the degradation of the reception sensitivity is prevented. Besides, at a timing when there is no reception signal, a reception system is disconnected from the antenna ( 11 ) by the switch ( 22 ), and the degradation of the transmission distortion characteristics is prevented.

TECHNICAL FIELD

The present invention relates to a mobile communication apparatus whichcan perform a transmission/reception simultaneous operation, andparticularly to a structure of an antenna switching part for switchingand connecting an antenna to a transmission system and a receptionsystem.

BACKGROUND ART

In a mobile communication system using a cellular phone or the like as amobile station terminal, in addition to a voice phone call, datacommunication by packet communication and the like are enabled. Ascable-free packet communication, in recent years, it is proposed toimprove a data transfer rate by enabling transmission and reception atthe same time. Then, as a portable mobile communication apparatus whichcan be used for such a mobile communication system, one which supports atransmission/reception simultaneous operation is requested from themarket.

In a mobile communication apparatus which does not perform transmissionand reception at the same time, since a transmission system has littleinfluence on a reception system, degradation of reception sensitivitydue to a transmission wave does not have to be considered, and anantenna sharing unit including filters is not required. Accordingly, inthe mobile communication apparatus which does not support thetransmission/reception simultaneous operation, as shown in FIG. 5, astructure is generally adopted in which an antenna sharing unit is notprovided, but only an antenna switching unit 102 is provided.

The mobile communication apparatus not supporting thetransmission/reception simultaneous operation and shown in FIG. 5 hassuch a structure that the antenna switching unit 102 for switchingbetween a transmission system and a reception system is connected to anantenna 101, and a filter is not provided. In the antenna switching unit102, a transmission side switch 111 is connected to a transmitting poweramplifier 103 and is connected to a transmission part 106. Besides, areception side switch 112 is connected to a reception side filter 104for removing an interfering wave and a receiving amplifier 105 insequence, and is connected to a reception part 107. Besides, there isprovided a switching control part 115 for performing connectionswitching control of the switches 111 and 112 of the antenna switchingunit 102.

In this structure, the switches 111 and 112 of the antenna switchingunit 102 are switched by the switching control part 115, and the antenna101 is connected to either one of the transmission system and thereception system. For example, in the case where only transmission isperformed at the time of a voice phone call or the like, the switch 111is connected, and the switch 112 becomes unconnected. In the case whereonly reception is performed at the time of a voice phone call or thelike, the switch 111 becomes unconnected, and the switch 112 isconnected. The switching control of the switches 111 and 112 isperformed by control signals from the switching control part 115.

On the other hand, in a mobile communication apparatus supporting atransmission/reception simultaneous operation, there occurs a state inwhich a transmission system and a reception system use the same antennalat the same time, and the transmission system has a large influence onthe reception system, and therefore, when the transmission system andthe reception system are simply connected to the antenna, receptionbecomes impossible. Thus, in the mobile communication apparatussupporting the transmission/reception simultaneous operation, an antennasharing unit including filters at the transmission side and thereception side is required, and a structure in which an antenna sharingunit 122 is provided as shown in FIG. 6 is generally used.

The mobile communication apparatus supporting the transmission/receptionsimultaneous operation shown in FIG. 6 has such a structure that theantenna sharing unit 122 including a transmission side filter 131 and areception side filter 132 is connected to an antenna 101. Thetransmission side filter 131 of the antenna sharing unit 122 isconnected to a transmitting power amplifier 103 and is connected to atransmission part 106. The reception side filter 132 is connected to areceiving amplifier 105 and is connected to a reception part 107. Inthis structure, the antenna 101 is always connected to the transmissionsystem and the reception system, and the simultaneous operation oftransmission and reception is enabled. At this time, a transmissionsignal from the transmission part 106 is cut off by the reception sidefilter 132 and is not inputted to the reception system, and a receptionsignal from the antenna 101 is cut off by the transmission side filter131 and is not inputted to the transmission system.

In the mobile communication apparatus supporting thetransmission/reception simultaneous operation as stated above, in thecase where the transmission/reception simultaneous operation isperformed by packet communication or the like, since there occurs astate in which the reception system and the transmission system areconnected, a shift occurs in the input impedance of the reception systemby the influence of the output impedance of the transmission system, andthere has been a fear that reception sensitivity is degraded. Besides,in this case, a shift occurs in the output impedance of the transmissionsystem by the influence of the input impedance of the reception system,and there has been a fear that distortion characteristics are degraded.

The present invention has been made in view of the above circumstances,and an object thereof is to provide a mobile communication apparatus inwhich in a mobile communication apparatus being able to perform atransmission/reception simultaneous operation, in a case wheretransmission/reception is performed by packet communication or the like,the degradation of reception sensitivity at a timing when there is notransmission signal is prevented, and the reception sensitivity can beimproved.

Besides, another object thereof is to provide a mobile communicationapparatus in which in a mobile communication apparatus being able toperform a transmission/reception simultaneous operation, in a case wheretransmission/reception is performed by packet communication or the like,the degradation of transmission distortion characteristics at a timingwhen there is no reception signal is prevented, and the transmissiondistortion characteristics can be improved.

DISCLOSURE OF THE INVENTION

A mobile communication apparatus according to a first structure of theinvention is a mobile communication apparatus, including a transmissionsystem for processing a transmission signal, a reception system forprocessing a reception signal, and an antenna connected to thetransmission system and the reception system, and allowing to perform atransmission/reception simultaneous operation. The mobile communicationapparatus comprises an antenna switch, which disconnects thetransmission system from the antenna during a period when only areception is performed in a case that the transmission/receptionsimultaneous operation is performed by the transmission system and thereception system.

According to the above structure, when the transmission/receptionsimultaneous operation is performed, for example, in the case wherepacket communication is performed, as the period in which only thereception is performed, at the timing when there is no transmissionsignal, such as the time when full slot transmission is not performed,the transmission system is disconnected from the antenna by the antennaswitch, so that the transmission system and the reception system can beseparated, and it becomes possible to prevent the reception sensitivityfrom being degraded by the influence of the output impedance of thetransmission system. Besides, for example, at the timing when there isno transmission signal and only the reception processing is performed,and in a period in which there is no reception information in thereception signal, the transmission system is disconnected from theantenna, so that it becomes possible to prevent the corruption of thereception information due to instantaneous impedance variation occurringat the switching timing of the antenna.

A mobile communication apparatus according to a second structure of theinvention is a mobile communication apparatus including a transmissionsystem for processing a transmission signal, a reception system forprocessing a reception signal, and an antenna connected to thetransmission system and the reception system, and allowing to perform atransmission/reception simultaneous operation. The mobile communicationapparatus includes an antenna switch, which disconnects the receptionsystem from the antenna during a period when only a transmission isperformed in a case that the transmission/reception simultaneousoperation is performed by the transmission system and the receptionsystem.

According to the above structure, when the transmission/receptionsimultaneous operation is performed, for example, in the case wherepacket communication is performed, as the period in which only thetransmission is performed, at the timing when there is no receptionsignal, such as the time when full slot reception is not performed, thereception system is disconnected from the antenna by the antenna switch,so that the transmission system and the reception system can beseparated, and it becomes possible to prevent the transmissiondistortion characteristics from being degraded by the influence of theinput impedance of the reception system. Besides, for example, at thetiming when there is no reception signal and only the transmissionprocessing is performed, and in a period in which there is notransmission information in the transmission signal, the receptionsystem is disconnected from the antenna, so that it becomes possible toprevent the corruption of the transmission information due toinstantaneous impedance variation occurring at the switching timing ofthe antenna.

Besides, the first structure is characterized in that the antenna switchincludes a first switch, which connects the antenna to the transmissionsystem in a case that a transmission operation is performed, a secondswitch, which connects the antenna to a filter constituting a receptionside antenna sharing unit in the reception system in a case that areception operation is performed and in the case that thetransmission/reception operation is performed, and a third switch, whichconnects a filter constituting a transmission side antenna sharing unitbetween the antenna and the transmission system in the case that thetransmission/reception operation is performed. The first switch and thethird switch are disconnected during the period when only the receptionis performed in the case that the transmission/reception simultaneousoperation is performed.

According to the above structure, when the transmission/receptionsimultaneous operation is performed, for example, in the case where thepacket communication is performed, the first and the third switches areopened in the period in which only the reception is performed, so thatthe transmission system is disconnected from the antenna, and thetransmission system and the reception system can be separated, and itbecomes possible to prevent the degradation of reception sensitivity dueto the influence of the output impedance of the transmission system.

Besides, the first structure is characterized in that the antenna switchincludes a first switch, which connects the antenna to a filterconstituting a transmission side antenna sharing unit in thetransmission system in a case that a transmission operation is performedand in the case that the transmission/reception operation is performed,and a second switch, which connects the antenna to a filter constitutinga reception side antenna sharing unit in the reception system in a casethat a reception operation is performed and in the case where thetransmission/reception operation is performed. The first switch isdisconnected during the period when only the reception is performed inthe case that the transmission/reception simultaneous operation isperformed.

According to the above structure, when the transmission/receptionsimultaneous operation is performed, for example, in the case where thepacket communication is performed, the first switch is opened in theperiod in which only the reception is performed, so that thetransmission system is disconnected from the antenna, and thetransmission system and the reception system can be separated, and itbecomes possible to prevent the degradation of reception sensitivity dueto the influence of the output impedance of the transmission system.

Besides, the second structure is characterized in that the antennaswitch includes a first switch, which connects the antenna to thetransmission system in a case that a transmission operation isperformed, a second switch, which connects the antenna to a filterconstituting a reception side antenna sharing unit in the receptionsystem in a case that a reception operation is performed and in the casethat the transmission/reception operation is performed, and a thirdswitch, which connects a filter constituting a transmission side antennasharing unit between the antenna and the transmission system in the casethat the transmission/reception operation is performed. The secondswitch is disconnected during the period when only the transmission isperformed in the case that the transmission/reception simultaneousoperation is performed.

According to the above structure, when the transmission/receptionsimultaneous operation is performed, for example, in the case where thepacket communication is performed, the second switch is opened in theperiod in which only the transmission is performed, so that thereception system is disconnected from the antenna, and the transmissionsystem and the reception system can be separated, and it becomespossible to prevent the degradation of transmission distortioncharacteristics due to the influence of the input impedance of thetransmission system.

Besides, the second structure is characterized in that the antennaswitch includes a first switch, which connects the antenna to a filterconstituting a transmission side antenna sharing unit in thetransmission system in a case that a transmission operation is performedand in the case that the transmission/reception operation is performed,and a second switch, which connects the antenna to a filter constitutinga reception side antenna sharing unit in the reception system in a casethat a reception operation is performed and in the case that thetransmission/reception operation is performed. The second switch isdisconnected during the period when only the transmission is performedin the case that the transmission/reception simultaneous operation isperformed.

According to the above structure, when the transmission/receptionsimultaneous operation is performed, for example, in the case where thepacket communication is performed, the second switch is opened in theperiod in which only the transmission is performed, so that thereception system is disconnected from the antenna, and the transmissionsystem and the reception system can be separated, and it becomespossible to prevent the degradation of transmission distortioncharacteristics due to the influence of the input impedance of thereception system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a structure of a main part of a mobilecommunication apparatus according to a first and a second embodiments;

FIG. 2 is an operation explanatory view showing an antenna switchingoperation of a mobile communication apparatus according to the first anda third embodiments of the invention;

FIG. 3 is an operation explanatory view showing an antenna switchingoperation of a mobile communication apparatus according to the secondand a fourth embodiments of the invention;

FIG. 4 is a block diagram showing a structure of a main part of themobile communication apparatus according to the third and the fourthembodiments;

FIG. 5 is a block diagram showing a structural example of a mobilecommunication apparatus not supporting a transmission/receptionsimultaneous operation; and

FIG. 6 is a block diagram showing a structural example of a mobilecommunication apparatus supporting a transmission/reception simultaneousoperation.

Incidentally, with respect to symbols in the drawing, 11 denotes anantenna; 12, a transmission side filter (antenna sharing unit); 13, atransmitting power amplifier; 14, a reception side filter (antennasharing unit); 15, a receiving amplifier; 16, 31, an antenna switchingunit; 17, a transmission part; 18, a reception part; 19, 32, a switchingcontrol part; and 21, 22, 23, 24, 41, 42; a switch.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the drawings.

First Embodiment

FIG. 1 is a block diagram showing a structure of a main part of a mobilecommunication apparatus according to a first embodiment.

In this embodiment, a structure of a connection part between atransmission/reception part of a cellular phone used as a mobile stationterminal of a mobile communication system and an antenna is shown as anexample of the mobile communication apparatus of the invention. Themobile communication apparatus of this embodiment supports packetcommunication in a TDMA (Time Division Multiple Access) system, and isconstructed to enable a transmission/reception simultaneous operation.

As shown in FIG. 1, the mobile communication apparatus of the firstembodiment is provided with an antenna 11 for performing transmissionand reception of a radio signal, and an antenna switching unit 16 forswitching the connection of the antenna 11 is connected. A transmissionside filter 12 constituting an antenna sharing unit and for cutting offa reception signal, and a transmitting power amplifier 13 for amplifyinga transmission signal are connected in sequence to a transmission sideof the antenna switching unit 16, and are connected to a transmissionpart 17. A reception side filter 14 constituting the antenna sharingunit and for cutting off a reception interfering wave and a transmissionsignal, and a receiving amplifier 15 for amplifying a reception signalare connected in sequence to a reception side of the antenna switchingunit 16, and is connected to a reception part 18.

The antenna switching unit 16 includes a switch 21 for connecting theantenna 11 to the transmitting power amplifier 13 in a case where onlytransmission is performed in a voice phone call or the like, a switch 22for connecting the antenna 11 to the reception side filter 14 in a casewhere only reception is performed in the voice phone call or the likeand in a case where transmission/reception is performed by packetcommunication or the like, and switches 23 and 24 for connecting thetransmission side filter 12 between the antenna 11 and the transmittingpower amplifier 13 in the case where the transmission/reception isperformed by the packet communication or the like. Besides, there isprovided a switching control part 19 for performing switching control ofconnection and unconnection of the switches 21, 22, 23 and 24 of theantenna switching unit 16. The switching control of the switches 21 to24 is performed by control signals from the switching control part 19irrespective of interlocking or non-interlocking.

Next, a description will be given to the operation of the mobilecommunication apparatus of this embodiment, mainly to the operation ofthe antenna switching unit 16.

In the case where a voice phone call or the like is made, and at atiming when only transmission is performed, only the switch 21 of theantenna switching unit 16 is connected. At this time, a transmissionsignal outputted from the transmission part 17 is amplified by thetransmitting power amplifier 13, and is transmitted and outputted to anot-shown base station from the antenna 11 through the switch 21 of theantenna switching unit 16, not through the transmission side filter 12.

In the case where a voice phone call is made, and at a timing when onlyreception is performed, only the switch 22 of the antenna switching unit16 is connected. At this time, a reception signal received by theantenna 11 is inputted to the reception side filter 14 through theswitch 22 of the antenna switching unit 16, and after an interferingwave is removed by the reception side filter 14, the signal is amplifiedby the receiving amplifier 15 and is inputted to the reception part 18,and a reception processing such as demodulation is performed.

In the case where packet communication is performed in the TDMA system,a transmission system and a reception system are made to operate at thesame time. Especially, in the case where full slot packet communicationto transmit packet data by using all usable time slots is performed, atransmission slot and a reception slot temporally overlap with eachother, and a transmission/reception simultaneous operation state occurs.In this case, the switches 22, 23 and 24 of the antenna switching unit16 are connected, so that there occurs a state in which the antennaswitching unit including the transmission side filter 12 and thereception side filter 14 is connected to the antenna 11, and both thetransmission system and the reception system are connected to theantenna 11 through the antenna sharing unit.

At this time, a transmission signal outputted from the transmission part17 is amplified by the transmitting power amplifier 13, and istransmitted and outputted to the not-shown base station from the antenna11 through the switch 24 of the antenna switching unit 16, thetransmission side filter 12, and the switch 23 of the antenna switchingunit 16. Here, the impedance of the reception system viewed from thetransmission side is almost infinite by the reception side filter 14,and the transmission signal is cut off by the reception side filter 14and does not flow to the reception system. Besides, a reception signalreceived by the antenna 11 is amplified by the receiving amplifier 15after an interfering wave is removed by the reception side filter 14through the switch 22 of the antenna switching unit 16 and the receptionside filter 14, and is inputted to the reception part 18, and areception processing such as demodulation is performed. Here, theimpedance of the transmission system viewed from the reception side isalmost infinite by the transmission side filter 12, and the receptionsignal is cut off by the transmission side filter 12 and does not flowto the transmission system.

In the case where the transmission/reception simultaneous operation asdescribed above is performed, when the antenna sharing unit is merelyprovided, there occurs a state in which the reception system and thetransmission system are always connected, and therefore, a shift occursin the input impedance of the reception system by the influence of theoutput impedance of the transmission system, and there is a fear thatthe reception sensitivity is degraded.

Then, in this embodiment, also at the time of the transmission/receptionsimultaneous operation such as the time of the packet communication, forexample, when full slot transmission is not performed, there is a timingwhen a transmission signal does not exist, and therefore, in a period inwhich only such a reception processing is performed, the transmissionsystem is made unconnected by the antenna switching unit 16, and thetransmission system and the reception system are separated.Specifically, in the period in which there is no transmission signal, aswitching control signal is sent to the antenna switching unit 16 fromthe switching control part 19, and the switches 21 and 23 of the antennaswitching unit 16 are made unconnected. By this, the transmission systemand the reception system can be separated, the degradation of thereception sensitivity in the period in which there is no transmissionsignal is prevented, and telephone call quality can be secured.

FIG. 2 is an operation explanatory view showing an antenna switchingoperation of the mobile communication apparatus according to the firstembodiment of the invention, and shows an example of the switchingcontrol timing of the antenna in a period in which there is notransmission signal. This drawing shows timings of a transmission signaland a reception signal in respective ones of a transmission slot and areception slot, and a control timing of connection switching of theantenna switching unit 16.

As shown in FIG. 2, at the timing when there is no transmission signaland only the reception processing is performed, and at the controltiming in a period T1 in which there is no reception information in thereception signal, the switches 21 and 23 of the antenna switching unit16 are opened to make the transmission system unconnected. By this, itbecomes possible to prevent the corruption of the reception informationdue to instantaneous impedance variation occurring at the switchingtiming of the antenna.

As stated above, in this embodiment, at the time when thetransmission/reception simultaneous operation is performed, such as thetime of the packet communication, and for example, in the case wherefull slot transmission is not performed, the transmission system isdisconnected from the antenna at the timing when there is notransmission signal, so that the transmission system and the receptionsystem can be separated, and the degradation of the receptionsensitivity can be prevented. By this, as compared with the case wherethe transmission system and the reception system are connected, forexample, the reception sensitivity can be improved by about 1 dB.

Second Embodiment

A second embodiment shows an example of switching control of an antennaat a timing when there is no reception signal in the structure of thefirst embodiment.

As described above, in the case where the packet communication isperformed in the TDMA system, the transmission system and the receptionsystem are operated at the same time. Especially, in the case where thefull slot packet communication to transmit packet data by using allusable time slots is performed, the transmission slot and the receptionslot temporally overlap with each other, and the transmission/receptionsimultaneous operation state occurs. At this time, the switches 22, 23and 24 of the antenna switching unit 16 are connected, so that thereoccurs a state in which the antenna sharing unit including thetransmission side filter 12 and the reception side filter 14 isconnected to the antenna 11, and both the transmission system and thereception system are connected to the antenna 11 through the antennasharing unit.

In the case where the transmission/reception simultaneous operation asstated above is performed, when the antenna sharing unit is merelyprovided, there occurs a state where the reception system and thetransmission system are always connected, and therefore, a sift occursin the output impedance of the transmission system by the influence ofthe input impedance of the reception system, and there is a fear thattransmission distortion characteristics are degraded.

Then, in this embodiment, also at the time of the transmission/receptionsimultaneous operation such as the time of the packet communication, forexample, when full slot reception is not performed, there is a timingwhen a reception signal does not exist, and therefore, in the period inwhich only such a transmission processing is performed, the receptionsystem is made unconnected by the antenna switching unit 16, and thetransmission system and the reception system are separated.Specifically, in the period of the timing when there is no receptionsignal, a switching control signal is sent to the antenna switching unit16 from the switching control part 19, and the switch 22 of the antennaswitching unit 16 is made unconnected. By this, the transmission systemand the reception system can be separated, the degradation oftransmission distortion characteristics in the period in which there isno reception signal is prevented, and the quality of a telephone callcan be secured.

FIG. 3 is an operation explanatory view showing an antenna switchingoperation of the mobile communication apparatus according to the secondembodiment of the invention, and shows an example of the switchingcontrol timing of the antenna in the period in which there is noreception signal. This drawing shows timings of a transmission signaland a reception signal in respective ones of a transmission slot and areception slot, and a control timing of connection switching of theantenna switching unit 16.

As shown in FIG. 3, at the timing when there is no reception signal andonly the transmission processing is performed, and at a control timingin a period T2 in which there is no transmission information in thetransmission signal, the switch 22 of the antenna switching unit 16 isopened to make the reception system connected. By this, it becomespossible to prevent the corruption of the transmission information dueto instantaneous impedance variation occurring at the switching timingof the antenna.

As stated above, in this embodiment, at the time when thetransmission/reception simultaneous operation is performed, such as thetime of the packet communication, and for example, in the case wherefull slot reception is not performed, the reception system isdisconnected from the antenna at the timing when there is no receptionsignal, so that the transmission system and the reception system can beseparated, and the degradation of the transmission distortioncharacteristics can be suppressed. By this, as compared with the casewhere the transmission system and the reception system are connected,for example, adjacent channel leakage power can be improved by about 0.5dB.

Third Embodiment

FIG. 4 is a block diagram showing a structure of a main part of a mobilecommunication apparatus according to a third embodiment of theinvention.

As shown in FIG. 4, the mobile communication apparatus of the thirdembodiment is provided with an antenna 11 for performing transmissionand reception of a radio signal, and an antenna switching unit 31 forswitching the connection of this antenna 11 is connected. A transmissionside filter 12 constituting an antenna sharing unit and for cutting offa reception signal and a transmitting power amplifier 13 for amplifyinga transmission signal are connected in sequence to a transmission sideof the antenna switching unit 31, and are connected to a transmissionpart 17. A reception side filter 14 constituting the antenna sharingunit and for cutting off a reception interfering wave and a transmissionsignal, and a receiving amplifier 15 for amplifying a reception signalare connected in sequence to a reception side of the antenna switchingunit 31, and are connected to a reception part 18.

The antenna switching unit 31 includes a switch 41 for connecting theantenna 11 to the transmission side filter 12 in a case where onlytransmission is performed by a voice phone call or the like and in acase where transmission/reception is performed by packet communicationor the like, and a switch 42 for connecting the antenna 11 to thereception side filter 14 in a case where only reception is performed bythe voice phone call or the like and in the case where thetransmission/reception is performed by the packet communication or thelike. Besides, there is provided a switching control part 32 forperforming switching control of connection and unconnection of theswitches 41 and 42 of the antenna switching unit 31. The switchingcontrol of the switches 41 and 42 is performed by control signals fromthe switching control part 32 irrespective of interlocking ornon-interlocking.

Next, a description will be given to the operation of the mobilecommunication apparatus of this embodiment, mainly to the operation ofthe antenna switching unit 31.

In the case where a voice phone call is made, and at a timing when onlytransmission is performed, only the switch 41 of the antenna switchingunit 31 is connected. At this time, a transmission signal outputted fromthe transmission part 17 is amplified by the transmitting poweramplifier 13, and is transmitted and outputted to a not-shown basestation from the antenna 11 through the transmission side filter 12 andthe switch 41 of the antenna switching unit 31.

In the case where the voice phone call is performed, and at a timingwhen only reception is performed, only the switch 42 of the antennaswitching unit 31 is connected. At this time, a reception signalreceived by the antenna 11 is inputted to the reception side filter 14through the switch 42 of the antenna switching unit 31, and after aninterfering wave is removed by the reception side filter 14, the signalis amplified by the receiving amplifier 15 and is inputted to thereception part 18, and a reception processing such as demodulation isperformed.

In the case where packet communication is performed in the TDMA system,a transmission system and a reception system are made to operate at thesame time. Especially, in the case where full slot packet communicationto transmit packet data by using all usable time slots is performed, atransmission slot and a reception slot temporally overlap with eachother, and a transmission/reception simultaneous operation state occurs.In this case, the switches 41 and 42 of the antenna switching unit 31are connected, so that there occurs a state in which the antenna sharingunit including the transmission side filter 12 and the reception sidefilter 14 is connected to the antenna 11, and both the transmissionsystem and the reception system are connected to the antenna 11 throughthe antenna sharing unit.

At this time, a transmission signal outputted from the transmission part17 is amplified by the transmitting power amplifier 13, and istransmitted and outputted to the not-shown base station from the antenna11 through the transmission side filter 12 and the switch 41 of theantenna switching unit 31. Here, the impedance of the reception systemviewed from the transmission side is almost infinite by the receptionside filter 14, and the transmission signal is cut off by the receptionside filter 14 and does not flow to the reception system. A receptionsignal received by the antenna 11 is amplified by the receivingamplifier 15 after an interfering wave is removed by the reception sidefilter 14 through the switch 42 of the antenna switching unit 31 and thereception side filter 14, and is inputted to the reception part 18, anda reception processing such as demodulation is performed. Here, theimpedance of the transmission system viewed from the reception side isalmost infinite by the transmission side filter 12, and the receptionsignal is cut off by the transmission side filter 12 and does not flowto the transmission system.

In the case where the transmission/reception simultaneous operation asstated above is performed, when the antenna sharing unit is merelyprovided, there occurs a state where the reception system and thetransmission system are always connected, and accordingly, a shiftoccurs in the input impedance of the reception system by the influenceof the output impedance of the transmission system, and there is a fearthat the reception sensitivity is degraded.

Then, in this embodiment, similarly to the first embodiment, also at thetime of the transmission/reception simultaneous operation such as thetime of the packet communication, for example, when full slottransmission is not performed, there is a timing when a transmissionsignal does not exist, and therefore, in the period in which only such areception processing is performed, the transmission system is madeunconnected by the antenna switching unit 31 to separate thetransmission system and the reception system. Specifically, in theperiod of the timing when there is no transmission signal, a switchingcontrol signal is sent to the antenna switching unit 31 from theswitching control part 32, and the switch 41 of the antenna switchingunit 31 is made unconnected. By this, the transmission system and thereception system can be separated, and the degradation of the receptionsensitivity in the period in which there is no transmission signal isprevented.

Besides, as shown in FIG. 2, similarly to the first embodiment, at thetiming when there is no transmission signal and only the receptionprocessing is performed, and at the control timing in the period T1 inwhich there is no reception information in the reception signal, theswitch 41 of the antenna switching unit 31 is opened, and thetransmission system is made unconnected. By this, it becomes possible toprevent the corruption of the reception information due to instantaneousimpedance variation occurring at the switching timing of the antenna.

As stated above, in this embodiment, similarly to the first embodiment,at the time when the transmission/reception simultaneous operation isperformed, such as the time of the packet communication, thetransmission system is disconnected from the antenna at the timing whenthere is no transmission signal, so that the transmission system and thereception system are separated, and the degradation of the receptionsensitivity can be suppressed, and as compared with the case where thetransmission system and the reception system are connected, for example,the reception sensitivity can be improved by about 1 dB.

Fourth Embodiment

A fourth embodiment shows an example of switching control of an antennaat a timing when there is no reception signal in the structure of thethird embodiment.

As described above, in the case where the packet communication isperformed in the TDMA system, a transmission system and a receptionsystem are made to operate at the same time. Especially, in the casewhere full slot packet communication to transmit packet data by usingall usable time slots is performed, a transmission slot and a receptionslot temporally overlap with each other, and a transmission/receptionsimultaneous operation state occurs. At this time, the switches 41 and42 of the antenna switching unit 31 are connected, so that there occursa state in which the antenna sharing unit including the transmissionside filter 12 and the reception side filter 14 is connected to theantenna 11, and both the transmission system and the reception systemare connected to the antenna 11 through the antenna sharing unit.

In the case where the transmission/reception simultaneous operation asstated above is performed, when the antenna sharing unit is merelyprovided, there occurs a state where the reception system and thetransmission system are always connected, and accordingly, a sift occursin the output impedance of the transmission system by the influence ofthe input impedance of the reception system, and there is a fear thatthe transmission distortion characteristics are degraded.

Then, in this embodiment, also at the time of the transmission/receptionsimultaneous operation such as the time of the packet communication, forexample, at the time when full slot reception is not performed, there isa timing when a reception signal does not exist, and therefore, in theperiod in which only such a transmission processing is performed, thereception system is made unconnected by the antenna switching unit 31,and the transmission system and the reception system are separated.Specifically, in a period of a timing when there is no reception signal,a switching control signal is sent to the antenna switching unit 31 fromthe switching control part 32, and the switch 42 of the antennaswitching unit 31 is made unconnected. By this, the transmission systemand the reception system can be separated, and the degradation oftransmission distortion characteristics in the period in which there isno reception signal is prevented.

Besides, as shown in FIG. 3, similarly to the second embodiment, at thetiming when there is no reception signal and only the transmissionprocessing is performed, and at the control timing in the period T2 inwhich there is no transmission information in the transmission signal,the switch 42 of the antenna switching unit 31 is opened, and thereception system is made unconnected. By this, it becomes possible toprevent the corruption of the transmission information due toinstantaneous impedance variation occurring at the switching timing ofthe antenna.

As stated above, in this embodiment, similarly to the second embodiment,at the time when the transmission/reception simultaneous operation isperformed, such as the time of the packet communication, the receptionsystem is disconnected from the antenna at the timing when there is noreception signal, so that the transmission system and the receptionsystem are separated, and the degradation of transmission distortioncharacteristics can be suppressed. As compared with the case where thetransmission system and the reception system are connected, for example,adjacent channel leakage power can be improved by about 0.5 dB.

Although the invention has been described in detail with reference tothe specific embodiments, it is apparent for one of ordinary skill inthe art that various changes and modifications can be made withoutdeparting the spirit and scope of the present invention.

This application is based on Japanese Patent Application No. 2002-124366filed on Apr. 25, 2002, and the contents thereof are incorporated hereinby reference.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, in the mobilecommunication apparatus being able to perform the transmission/receptionsimultaneous operation, in the case where transmission/reception isperformed by the packet communication or the like, there are obtainedeffects that the degradation of reception sensitivity at the timing whenthere is no transmission signal is prevented, and the receptionsensitivity can be improved.

Besides, in the mobile communication apparatus being able to perform thetransmission/reception simultaneous operation, in the case wheretransmission/reception is performed by the packet communication or thelike, there are obtained effects that the degradation of transmissiondistortion characteristics at the timing when there is no receptionsignal is prevented, and the transmission distortion characteristics canbe improved.

1. A mobile communication apparatus, including a transmission system forprocessing a transmission signal, a reception system for processing areception signal, and an antenna connected to the transmission systemand the reception system, and allowing to perform atransmission/reception simultaneous operation, the mobile communicationapparatus, comprising: an antenna switch, which disconnects thetransmission system from the antenna during a period when only areception is performed in a case that the transmission/receptionsimultaneous operation is performed by the transmission system and thereception system.
 2. A mobile communication apparatus, including atransmission system for processing a transmission signal, a receptionsystem for processing a reception signal, and an antenna connected tothe transmission system and the reception system, and allowing toperform a transmission/reception simultaneous operation, the mobilecommunication apparatus, comprising: an antenna switch, whichdisconnects the reception system from the antenna during a period whenonly a transmission is performed in a case that thetransmission/reception simultaneous operation is performed by thetransmission system and the reception system.
 3. The mobilecommunication apparatus according to claim 1, wherein the antenna switchincludes: a first switch, which connects the antenna to the transmissionsystem in a case that a transmission operation is performed; a secondswitch, which connects the antenna to a filter constituting a receptionside antenna sharing unit in the reception system in a case that areception operation is performed and in the case that thetransmission/reception operation is performed; and a third switch, whichconnects a filter constituting a transmission side antenna sharing unitbetween the antenna and the transmission system in the case that thetransmission/reception operation is performed; and wherein the firstswitch and the third switch are disconnected during the period when onlythe reception is performed in the case that the transmission/receptionsimultaneous operation is performed.
 4. The mobile communicationapparatus according to claim 1, wherein the antenna switch includes: afirst switch, which connects the antenna to a filter constituting atransmission side antenna sharing unit in the transmission system in acase that a transmission operation is performed and in the case that thetransmission/reception operation is performed; and a second switch,which connects the antenna to a filter constituting a reception sideantenna sharing unit in the reception system in a case that a receptionoperation is performed and in the case where the transmission/receptionoperation is performed; and wherein the first switch is disconnectedduring the period when only the reception is performed in the case thatthe transmission/reception simultaneous operation is performed.
 5. Themobile communication apparatus according to claim 2, wherein the antennaswitch includes: a first switch, which connects the antenna to thetransmission system in a case that a transmission operation isperformed; a second switch, which connects the antenna to a filterconstituting a reception side antenna sharing unit in the receptionsystem in a case that a reception operation is performed and in the casethat the transmission/reception operation is performed; and a thirdswitch, which connects a filter constituting a transmission side antennasharing unit between the antenna and the transmission system in the casethat the transmission/reception operation is performed; and wherein thesecond switch is disconnected during the period when only thetransmission is performed in the case that the transmission/receptionsimultaneous operation is performed.
 6. The mobile communicationapparatus according to claim 2, wherein the antenna switch includes: afirst switch, which connects the antenna to a filter constituting atransmission side antenna sharing unit in the transmission system in acase that a transmission operation is performed and in the case that thetransmission/reception operation is performed; and a second switch,which connects the antenna to a filter constituting a reception sideantenna sharing unit in the reception system in a case that a receptionoperation is performed and in the case that the transmission/receptionoperation is performed; and wherein the second switch is disconnectedduring the period when only the transmission is performed in the casethat the transmission/reception simultaneous operation is performed.